Method and system for forming plug and play oxide catalysts

ABSTRACT

An oxide catalyst is formed by vaporizing a quantity of at least one precursor material or catalyst material thereby forming a vapor cloud. The vapor cloud is quenched forming precipitate nanoparticles. The nanoparticles are impregnated onto supports. The supports are able to be used in existing heterogeneous catalysis systems. A system for forming oxide catalysts comprises means for vaporizing a quantity of at least one precursor material or at least one catalyst material, quenching the resulting vapor cloud and forming precipitate nanoparticles. The system further comprises means for supports with the nanoparticles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application of U.S. patentapplication Ser. No. 13/921,066, filed Jun. 18, 2013, which is acontinuation application of U.S. patent application Ser. No. 12/001,644,filed Dec. 11, 2007, now U.S. Pat. No. 8,481,449, which claims prioritybenefit of U.S. Provisional Patent Application No. 60/999,057, filedOct. 15, 2007. The entire contents of those applications are herebyincorporated by reference herein.

BACKGROUND OF THE INVENTION

In the oil refining and fine chemical industries, catalysts are requiredto transform one chemical or one material into another. For example, tomake cyclohexane from benzene, benzene is passed through porous ceramicsupports that have been impregnated with catalysts designed andconfigured to hydrogenate it into cyclohexane. In one particularprocess, platinum is nitrated and impregnated onto supports in the wetchemical process 100 shown in FIG. 1. A platinum group metal, such asplatinum, osmium, ruthenium, rhodium, palladium or iridium, is collectedin step 101. For the sake of brevity, platinum will be discussed hereinbut it will be apparent to those of ordinary skill in the art thatdifferent platinum group metals can be used to take advantage of theirdifferent properties. Since blocks of elemental platinum are not useableas a catalyst, the platinum is nitrated in the step 102, forming a salt,specifically PtNO₃. The nitration is typically performed using wellknown methods of wet chemistry. The PtNO₃ is dissolved into a solventsuch as water in a step 103, causing the PtNO₃ to dissociate into Pt+and NO₃− ions. In the step 104, the salt is adsorbed onto the surfacesof supports 104B through transfer devices 104A, such as pipettes. Anexample of a support 104B is shown in FIG. 2. Generally, a support 104Bis a highly porous ceramic material that is commercially available in avast array of shapes, dimensions and pore sizes to accommodateparticular requirements of a given application. The supports 104B aredried to remove water then transferred to an oven for an air calciningstep 105. In the oven, the supports 104B are exposed to heat andoptionally pressure that causes the Pt+ to coalesce into elemental Ptparticles on the surfaces of the supports 104B. In the step 106, endproduct catalysts are formed. The end product is a support 104B that isimpregnated with elemental platinum. These supports are generally usedin catalytic conversion by placing them in reactors of variousconfigurations. For example, benzene is passed through the supports 104Bwhich convert the benzene into cyclohexane in the fine chemicalindustry. In the oil refining industry, the supports are used in asimilar fashion. The process steps are used to convert crude oil into auseable fuel or other desirable end product. The process described inFIG. 1 has opportunities for improvement. Although the platinum stickssufficiently well to the surface of the support 104 b, platinum atomsbegin to move and coalesce into larger particles at the temperaturesthat catalysis generally occurs. It is understood that the effectivenessand activity of a catalyst are directly proportional to the size of thecatalyst particles on the surface of the support. As the particlescoalesce into larger clumps, the particle sizes increase, the surfacearea of the catalyst decreases and the effectiveness of the catalyst isdetrimentally affected. As the effectiveness of the catalyst decreases,the supports 104B must be removed from the reactors and new supportsadded. During the transition period, output is stopped and overallthroughput is adversely affected. Also, platinum group metal catalystsare very expensive, and every addition of new supports comes at greatcost. What is needed is a plug and play catalyst that is usable incurrent oil refineries and fine chemical processing plants, allowing anincrease in throughput and decrease in costs.

SUMMARY OF THE INVENTION

A method of making an oxide catalyst comprises providing a quantity ofoxygen containing nanoparticles, providing a quantity of supports, andcombining the supports with the nanoparticles. In some embodiments, thesupports comprise voids and pores. Preferably, providing a quantity ofnanoparticles comprises loading a quantity of at least one precursormaterial into a plasma gun, vaporizing the at least one precursormaterial and quenching the at least one precursor material. Theprecursor material comprises any among a list of a metal, an oxide, asalt, a carbon compound and any combination thereof. Alternatively,providing a quantity of nanoparticles comprises loading a quantity of atleast one catalyst material into a plasma gun, vaporizing the at leastone catalyst material and quenching the at least one catalyst material.Preferably, combining the supports and nanoparticles comprisessuspending the nanoparticles in a solution, thereby forming a suspensionand mixing the suspension with a quantity of the supports.Alternatively, combining the supports and nanoparticles comprisessuspending the nanoparticles in a solution, thereby forming a suspensionand mixing the suspension with a slurry having porous supports suspendedtherein. The solution further comprises a dispersant. The slurrycomprises any among an organic solvent, an aqueous solvent, or acombination thereof. Preferably, the method further includes drying thesupports. Also, the method further comprises exposing the supports toany one of heat, pressure or a combination thereof, thereby calciningthe nanoparticles onto the supports.

A system for forming an oxide catalyst comprises means for providing aquantity of oxygen containing nanoparticles, means for collecting thenanoparticles, means for forming a suspension by mixing thenanoparticles into a liquid and means for combining the suspension witha quantity of supports. Preferably, the means for providing a quantityof nanoparticles comprises means for loading a quantity of at least oneprecursor material into a plasma gun, means for vaporizing the precursormaterial thereby forming a vapor cloud and means for quenching the vaporcloud thereby forming solid nanoparticles. Alternatively, the means forproviding a quantity of nanoparticles comprises means for loading aquantity of at least one catalyst material into a plasma gun, means forvaporizing the catalyst material thereby forming a vapor cloud and meansfor quenching the vapor cloud thereby forming solid nanoparticles. Thesystem further comprises means for drying the supports. The system alsocomprises means for exposing the supports to heat, thereby calcining thenanoparticles onto the supports. Preferably, the means for combining thesuspension with supports comprises means for impregnating supports withthe suspension. Alternatively, the means for combining the suspensionwith the supports comprises means for mixing the suspension with aslurry having supports. The slurry comprises any among an organicsolvent, and aqueous solvent, and a combination thereof. Preferably, thesuspension comprises an adjunct configured to cause the nanoparticles torepel each other in the solvent thereby suspending in the solvent.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is better understood by reading the following detaileddescription of an exemplary embodiment in conjunction with theaccompanying drawings.

FIG. 1 prior art illustrates an existing process for forming a usefulsupport for use in heterogenous catalysis.

FIG. 2 prior art shows a porous support generally used as a support inheterogeneous catalysis.

FIG. 3 shows the preferred embodiment of a novel process for forming asupport for use in heterogeneous catalysis.

FIG. 4A shows an example of a nanoparticle formed as part of the processof FIG. 3.

FIG. 4B shows a close up of an impregnated porous support.

FIG. 4C shows a close up of an impregnated macro support.

FIG. 5 shows an example of the supports being used as heterogeneouscatalysts.

FIG. 5A shows the hydrogenation of benzene into cyclohexane.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to implementations of the presentinvention as illustrated in the accompanying drawings. The drawings maynot be to scale. The same reference indicators will be used throughoutthe drawings and the following detailed description to refer toidentical or like elements. In the interest of clarity, not all of theroutine features of the implementations described herein are shown anddescribed. It will, of course, be appreciated that in the development ofany such actual implementation, numerous implementation-specificdecisions must be made in order to achieve the developer's specificgoals, such as compliance with application, safety regulations andbusiness related constraints, and that these specific goals will varyfrom one implementation to another and from one developer to another.Moreover, it will be appreciated that such a development effort will bea routine undertaking of engineering for those of ordinary skill in theart having the benefit of this disclosure.

The following description of the invention is provided as an enablingteaching which includes the best, currently known embodiment. Oneskilled in the relevant arts, including but not limited to chemistry andphysics, will recognize that many changes can be made to the embodimentdescribed, while still obtaining the beneficial results of the presentinvention. It will also be apparent that some of the desired benefits ofthe present invention can be obtained by selecting some of the featuresof the present invention without utilizing other features. Accordingly,those who work in the art will recognize that many modifications andadaptations to the present invention are possible and may even bedesirable in certain circumstances, and are a part of the presentinvention. Thus, the following description is provided as illustrativeof the principles of the present invention and not in limitationthereof, since the scope of the present invention is defined by theclaims. The terms “nanoparticle,” “nanoparticle powder,” and “nanopowder” are generally understood by those of ordinary skill to encompassa quantity of material comprising particles on the order of nanometersin diameter, as described herein.

FIG. 3 illustrates the inventive steps for a process 300 of forming a“plug and play” catalyst for use in such industries as chemicalmanufacturing. The method begins at the step 310. A quantity of at leastone precursor material 312 is loaded into a plasma gun 315. Preferably,the precursor 312 comprises any among an oxide, a metal, a metal oxide,a metal salt, a chlorine compound, phosphorous compound, or anycombination thereof. Alternatively, an oxide catalyst is loaded into theplasma gun 315. Oxides are well known and studied in the field ofchemistry. Many oxide combinations exist, each having applications inindustry. This disclosure focuses on oxides having catalytic properties.Oxides having catalytic properties include metal oxides, nonmetaloxides, and oxide-oxide bonded particles. Particularly, some oxides areused in heterogeneous catalysis, wherein the catalyst is in a differentphase than the reactants. Heterogeneous catalysts provide a surface forthe chemical reaction to take place on or otherwise activate thereaction. Next, in the step 320, the plasma gun 315 vaporizes theprecursor 312 to form a vapor cloud 325. By way of example, if thedesired oxide catalyst is lanthanum iron oxide, multiple permutations ofprecursor 312 are amenable to that end. One permutation includes loadinga quantity of pre-formed lanthanum iron oxide, a commercially availablematerial, into the plasma gun 315. Another permutation includes loadinga quantity of lanthanum oxide and iron into the gun 315. In stillanother permutation, lanthanum and iron are loaded into the plasma gun315 and the resulting vapor cloud 325 is combined with ambient oxygen.Alternatively, oxygen or an oxygen containing compound is injected intothe reaction chamber. Also, more complex oxides having multiplecomponents are contemplated. It will be apparent to those of ordinaryskill that many different permutations are amenable to the processdescribed herein with a vast array of starting compounds.

Still referring to FIG. 3, the resulting vapor cloud 325 is then putthrough a quenching step 330. Preferably, the quenching step occurs in ahighly turbulent quench chamber to facilitate rapid, even, consistentquenching of the vapor 325 into precipitate nanoparticles 400. Such arapid quench chamber is described in detail in U.S. patent applicationSer. No. 12/151,935, filed on May 8, 2008, which published as U.S.Patent Publication No. 2008-0277267 and is hereby incorporated byreference. As the gaseous oxide particles cool, they solidify intonanoparticles 400. An example of a resulting nanoparticle 400 is shownin FIG. 4A. The particles 400 will generally be in the range of 0.5 to200 nm in size, and can be as small as a molecular length of thecatalyst material and as large as would be achievable by ball milling.The particle size is able to be varied with varying starting materials,vaporization speeds, quench speeds and plasma temperatures.

In some embodiments, the process 300 continues with step 340, where thenanoparticles 400 are combined with a liquid to form a dispersion 345.Preferably, a liquid that will not react with the catalyst or precursormaterials is used. Some appropriate liquids are aqueous solutions ororganic solutions employing solvents such as alcohols, ethers,hydrocarbons, esters, amines, or the like. Since the nanoparticles 400are small, other precautions are generally taken to ensure that theysuspend evenly within the dispersion. To that end, an adjunct 348 isable to be added to the dispersion. The adjunct 348, also referred tocommonly in the art as a surfactant or dispersant, adheres to thenanoparticles 400 and causes them to repel each other, thereby causingthe nanoparticles 400 to suspend evenly in the dispersion 345. Thedispersion 345 is also referred to as a suspension.

Referring back to FIG. 3, it is important to note that nanoparticles 400such as the one shown in FIG. 4 are not generally compatible withexisting processes for chemical conversion. For compatibility withexisting processes, the nanoparticles 400 are bonded to a support. Whenthe nanoparticles 400 are bonded to a support, nanoparticle 400 providesa surface where reactions are able to take place or where reactions areactivated. To that end, more steps are taken to bring the nanoparticles400 to a useable form. To bring the nanoparticles 400 closer to a usablecatalyst, the nanoparticles 400 are impregnated onto supports 355. Thesupports 355 are also known to those skilled in the relevant art asporous oxides. Alternatively, the supports 355 are also referred to asextrudates because they are generally made using an extrusion process.The supports 355 are similar to the supports 104 b in FIGS. 1 and 2.Such supports have found utility due to their highly accessible andlarge surface area, as high as 250 m²/g. In alternative embodiments, amacroscopic support particle is able to be used. In such an embodiment,the size of the macroscopic support particle is selected to providemaximum surface area to which nanoparticles 400 are bonded or fixed. Thestep 350A shows the preferred embodiment of achieving the impregnation.The dispersion 345 is combined with a quantity of substantially dryporous supports 355A to form a mixture 359A. Alternatively, as shown inthe step 350B, the dispersion 345 is combined with a slurry 358 havingmacroscopic support particles 355B suspended therein, thereby formingthe mixture 359B. The slurry 358 is able to be a suspension of water,alcohol, or any suitable organic or inorganic liquid which will notreact with the macroscopic supports 355B or nanoparticles 400. In thestep 350A, capillary forces will draw in the dispersion 345, and in turnthe nanoparticles 400, into the various voids and pores within thestructure of the porous supports 355A, thereby forming impregnatedporous supports 365A. To aid in the impregnation, the mixture can beagitated or subjected to heat or pressure. In the step 350B,nanoparticles 400 come to rest on the surfaces of macroscopic supportsthereby forming impregnated macro supports 365B. In some embodiments,the steps 350A or 350B are repeated at least once for enhancedimpregnation.

Next, in the steps 360A and 360B, the impregnated porous supports 365Aor macro supports 365B are allowed to dry. A close up view theimpregnated porous support 365A is shown in FIG. 4B. As the liquid inthe dispersion 345 evaporates, the nanoparticles 400 settle onto thesurface of the support 365A and into the pores 367 within the support365A. FIG. 4C shows an example of an impregnated macro support 365B. Asthe liquids in the dispersion 345 and slurry 358 dry, nanoparticles 400settle onto the surface of the macro support 365B. When the impregnatedporous supports 365A or macro supports 365B dry, electrostaticinteractions and other non covalent forces between the nanoparticles 400and the porous supports 365A or macro supports 365B effectuate someadhesion. Advantageously, such forces cause the nanoparticles 400 tostick onto the surfaces and pores 367 of the supports 365A or 365B, andeffectuate transfer of the supports 365 through the remainder of theprocess 300. Referring back to FIG. 3, a calcining step 370A or 370B isperformed to form oxide-oxide bonds between the nanoparticles 400 andthe impregnated supports 365A or 365B by exposing them to heat 372,pressure 375, or a combination thereof. The calcining temperature isgenerally from 350 to 1000 degrees centigrade, and the pressure is onthe order of ambient atmosphere to several atmospheres. Due to thephysical and chemical bond between the supports 365A and 365B and thenanoparticles 400, islands of nanoparticles 400 that are bonded, fixedor otherwise pinned to the surfaces of the supports 365A or 365B willnot migrate and coalesce during catalytic conversion. The surface areafor catalysis remains high, and therefore the catalytic activity remainshigh. In effect, operations such as fine chemical plants and oilrefineries will not be required to stop operations and swap outineffective catalyst supports with fresh catalyst supports with the samefrequency as existing processes, thereby increasing throughput at theplants and refineries and reducing their overall cost of operation.

FIG. 5 shows an example of the impregnated porous supports 365A beingused in the fine chemical industry to hydrogenate benzene intocyclohexane. Macro supports 365B are able to be used as well. Althoughthis example details use in the fine chemical industry, it will beapparent to those of ordinary skill in the arts of chemistry, chemicalengineering, or the like that any process using heterogeneous catalysisis able to benefit from this disclosure. An amount of impregnated poroussupports 365A is loaded into a reactor 510. Preferably, the reactor 510has a mesh opening 515 on one end wherein the meshing has a smalleropening pitch than the size of the supports 365 such that the supports365 do not fall through the opening 515. Benzene is passed into the vat511 via the conduit 520. As the benzene passes through the vat 511, thebenzene fills into the voids and pores of the support 365A.

FIG. 5A shows an example of a benzene molecule 525 being hydrogenatedinto cyclohexane 525A in a cross section of a pore 367. When the benzenemolecule 525 comes into contact with the nanoparticle 400 that is bondedto the surface of the support 365A, nanoparticle 400 will effectuatehydrogenation of the benzene molecule 525 and hydrogen molecules 525Binto cyclohexane 525A without losing any energy to heat or riskinguncontrolled burning or combustion.

We claim:
 1. A supported catalyst, comprising: a. support structures,wherein the support structure comprises a porous oxide; and b.nanoparticles bonded to the support structures, wherein thenanoparticles comprise an oxide catalyst; wherein the nanoparticles areattached to the support structures by an oxide-oxide bond.
 2. Thesupported catalyst of claim 1, wherein the oxide catalyst comprises ametal oxide.
 3. The supported catalyst of claim 2, wherein the oxidecatalyst comprises lanthanum iron oxide.
 4. The supported catalyst ofclaim 1, wherein the nanoparticles are prepared using plasma.
 5. Thesupported catalyst of claim 1, wherein the support structures aremacroscopic particles.
 6. The supported catalyst of claim 1, wherein thenanoparticles are about 0.5 nanometers to about 200 nanometers indiameter.
 7. The supported catalyst of claim 1, wherein thenanoparticles are on the surface and in the pores of the supportstructures.
 8. The supported catalyst of claim 7, wherein thenanoparticles are deposited on the surface and in the pores of thesupport structures by suspending the nanoparticles in a solution to forma suspension, and mixing the suspension with the support structures. 9.The supported catalyst of claim 8, wherein the solution furthercomprises a dispersant.
 10. The supported catalyst of claim 8, whereinthe suspension of nanoparticles mixed with the support structures isdried, then exposed to heat, pressure, or a combination of heat andpressure to calcine the nanoparticles onto the support structures. 11.The supported catalyst of claim 7, wherein the nanoparticles aredeposited on the surface and in the pores of the support structures bysuspending the nanoparticles in a solution to form a suspension, andmixing the suspension with a slurry having the support structuressuspended therein.
 12. The supported catalyst of claim 11, wherein thesolution further comprises a dispersant.
 13. The supported catalyst ofclaim 1, wherein the nanoparticles comprise a metal oxide formed from aprecursor material, wherein the precursor material is selected from thegroup consisting of a metal, a metal oxide, a metal salt, a carboncompound, a chlorine compound, a phosphorous compound, and anycombination thereof.
 14. The supported catalyst of claim 1, wherein theoxide-oxide bond is formed by calcination.